The objective of this research is to understand how the auditory system perceives complex auditory spectra such as speech, music, or other broadband sounds. Experiments are proposed to various auditory spectra. Data from these experiments will provide detailed quantitative models of this process. A successful model of these auditory processes would provide a baseline from which to evaluate deviations from normal hearing that occur in the various hearing pathologies. The particular goal of the present experiments is to understand how the frequency of the components comprising the spectra affect these discriminating judgments. Especially important is to understand how very high frequencies influence these discrimination capacities. When the ear is damaged, either by loud noise or ototoxic drugs, the first noticeable changes occur in the higher frequency regions.